With Meldrum I think it's ego, ego, ego.
Mythical bigfoot is his only claim to fame and he's not going to back off at any time for any reason.
Consider that Meldrum is most likely a sincere believer in bigfoot, and he has tenure, so he can afford to indulge his interests. Since this kind of thing happens often enough--competent scientists veering off into pseudoscience--it's maybe worth pausing to consider the situation.
First, it does create amusement, where bigfoot enthusiasts who ordinarily hate science leap upon Meldrum like he's floating debris after a shipwreck. It seems as if an authority validates their beliefs, though this is not at all how science works. At the same time, Meldrum shows that the conspiracy theories involving bigfoot cover ups by governments and mainstream science is false, though they try not to think too hard about that.
Of course scientists aren't immune from errors of subjectivity. Meldrum must know that the evidence for bigfoot is not there, but he's betting that his feelings on the matter are correct, and that the work he's doing, which is not relevant now, will become relevant later when the existence of bigfoot is finally established.
Since bigfoot seems to be impossible, this will not play out well for Meldrum in the end, but it's okay, since he's losing nothing. He has tenure, the occasional spotlight, and his fantasy that he's on the cutting edge of something marvelous.
Good for him, I guess, but this shows how the process of science, as clumsy as it is, tends to do the right thing by simply ignoring the Meldrums of the world.
This must belong in the Meldrum thread, though. Sorry.